Dialkyltin oxides have traditionally been used as cure catalysts for electrodeposition coatings. Dialkyltin oxides, however, have been subjected to a number of regulatory restrictions by various countries due to environmental concerns. Therefore, bismuth has been used with increased frequency as the cure catalyst for electrodeposition coatings in lieu of dialkyltin oxide. There are, however, a number of shortcomings associated with using bismuth as the cure catalyst. For example, bismuth is often a less effective catalyst for various electrodeposition compositions when compared to dialkyltin oxide. Moreover, there may be cost and availability issues associated with using bismuth as a cure catalyst in the future. Accordingly, there is a need for an alternative catalyst for use in an electrodeposition coating. Moreover, there is also a need for an electrodeposition coating that is substantially free of tin.
One material being evaluated for use in electrodeposition coatings as a possible replacement for metal catalysts is cyclic guanidines such as bicyclic guanidines and bicyclic guanidine salts. Conventionally, bicyclic guanidines and bicyclic guanidine salts may be prepared in a variety of ways, but most known methods require high temperatures and long reaction times, or expensive and toxic reagents, or both. Ideally, it would be highly desirable to find a low cost, relatively safe, and efficient method for producing bicyclic guanidines and/or bicyclic guanidine salts.